Cleaning and laundry products are well known in the art. However, consumer acceptance of cleaning and laundry products is determined not only by the performance achieved with these products but also the aesthetics associated therewith. The perfume components are therefore an important aspect of the successful formulation of such commercial products.
Accordingly, formulations of compounds which provide a slow release of the perfume over a longer period of time than by the use of the perfume itself have been provided. Disclosure of such compounds may be found in WO 95/04809, WO 95/08976 and pending application EP 95303762.9. Pending application EP 95303762.9 describes betaine ester compounds of perfume alcohols which provide release of the perfume components over a long period of time.
Although betaine ester compounds are effective in the slow release of perfume, it has now been found that in an acidic environment such as in acidic product, the described compounds hydrolyse upon storage to release their perfume component, therefore reducing the amount of perfume alcohol released upon and after the washing or cleaning process. By acidic environment, it is meant a pH value of less than 7.0.
The formulator of a laundry and/or cleaning compositions is thus faced with the challenge of formulating a compound which is stable in an acidic environment but which still produces a slow release of the active alcohol (e.g perfume) upon and after the washing or cleaning process.
The Applicant has now found that the provision of betaine ester compounds of active alcohols in combination with a surfactant, wherein said betaine esters at a concentration of from 0.01% to 10% by weight are predominantly in the form of micelles, and/or are capable of being incorporated into micelles, overcomes the problem. Preferably, said betaine esters have at least one long alkyl chain.
Therefore, the present invention encompasses acidic compositions comprising betaine ester compounds of active alcohol components having a long alkyl chain, which at a concentration of from 0.01% to 10% by weight are predominantly in the form of micelles, and/or are capable of being incorporated into micelles, in combination with a surfactant. For optimum benefit of storage stability and slow release of the active alcohol upon and after the washing or cleaning process, a cationic surfactant is preferred.
Not to be bound by theory, it is believed that the use of betaine ester compounds with at least one long alkyl chain provide said betaine esters with a hydrophobic character which enable them to be rearranged in micelle form and/or to be incorporated into micelles, thereby protecting the ester bond from hydrolysis by the acidic environment.
For the purpose of the invention, the term "acidic aqueous composition" includes compositions having a pH value below or equal to 7.0, whereby the pH is measured at 20.degree. C. in the neat liquid product.
By "slow release" is meant release of the active component (e.g perfume) over a longer period of time than by the use of the active (e.g perfume) itself.
Accordingly, the slow release concept and storage stability advantage of the invention may be applied to other active alcohol components such as a flavour alcohol ingredient, a pharmaceutical alcohol active or a biocontrol alcohol agent and any other active alcohol component where a slow release of said active component is necessary.